When a British Special Forces soldier goes rogue, ex-MI5 controller Charlotte Button is hired to work out what his plan is and to take him down before he can carry it out. When the man returns to the UK it looks like the threat will be a lot closer to home. Charlotte puts her best man on the case – hitman Lex Harper. It's up to Lex to get to the soldier before he carries out what could be a massive terrorist attack. But Charlotte has her own problems – someone has broken into her safe deposit box, and she must work out who is after her and what they want.